The present invention relates generally to a rear end for a racing car used in sprint racing, and, more particularly, to a rear end having offset drive gears for transferring rotational power from the engine to the rear axle of the racing car.
Sprint cars and smaller racing cars are powered by an engine supported in a frame and connected to a rear end gear box that transfers rotational power to the rear wheels of the racing car. The rear end gear box has a disconnect mechanism that interrupts the transmission of rotational power to the rear wheels. When the racing car is being operated on the race track, the rear end gear box is engaged to transfer power from the engine. When the operator desires to stop the movement of the racing car, the rear end gear box is operably disconnected from the engine so that rotational power is no longer being transferred.
In current state of the art racing car rear ends, the drive shaft connected between the engine and the rear end gear box transfers a substantial amount of power to the rear end. In some sprint cars, the engine can produce 950 horsepower to drive the racing car which may weigh only about 1300 pounds. The torque involved in the transfer of this much power, along with the external forces encountered during the racing of the sprint car, results in a movement of the drive shaft relative to the rear end. This slight “whipping” and vibrational movement of the drive shaft can place substantial wear on the bearings housed within the rear end. To minimize the wear problem, a swivel coupling has been adopted so that the swivel coupling can absorb the movement of the drive shaft without causing substantial wear problems.
The placement of a swivel coupling into the engine end of the rear end gear box causes spatial problems. Because of the ring gear contained within the rear end gear box to drive the rear axle of the racing car, the swivel coupling and a bearing for rotationally supporting the swivel coupling are located on the outside of the rear end housing. As a result, the bearing has to be a sealed bearing that contains its own lubricant, since the bearing is not in flow communication with the oil flow within the rear end housing. If the swivel coupling were located inside the conventional gear box, the interior portion of the swivel coupling would interfere with the ring gear. Accordingly, the swivel coupling is positioned outside the rear end housing where stability and rigidity of the swivel coupling is compromised. Furthermore, the swivel coupling is not lubricated from the oil within the rear end housing.
Sprint racing cars only turn to the left when racing around the track. Manufacturers have employed different strategies for shifting the center of gravity of the racing car to the left of the car centerline. One concept was to shift the engine to the left of the car centerline; however, the resulting coupling of the drive shaft between the engine and the rear end placed too much stress on the swivel coupler, reducing the life of the swivel coupler. Extending the life of the bearings and the swivel coupler is important to successful operation of the racing cars. If the swivel coupler or the bearings fail during a race, the race car is finished for the night.
Therefore, it would be desirable to provide a rear end structure for a racing car that would be operable to recess the swivel coupler and the associated bearing internal of the rear end housing so that the swivel coupler and the bearing would be lubricated by the oil within the rear end housing. It would also be desirable to provide a rear end structure for a racing car that results in a shifting of the center of gravity of the racing car to the left to increase the stability of the racing car while make turns on the race track.